Vehicle beat noise determination device

Abstract

To provide a device capable of determining a beat noise that may occur in a specific running state of a vehicle in order to enable taking measures to reduce the beat noise.SOLUTION: A beat noise determination device for a vehicle that determines beat noise by analyzing sound data generated from a vehicle having a driving force source for each wheel while the vehicle is running, extracts sounds with a predetermined sound pressure or higher as protruding sounds, determines a protruding sound whose frequency difference is within a predetermined range and whose sound pressure difference is less than a predetermined value to be a beat noise, and determines whether a source of the detected beat noise is the driving force source on the basis of the determined frequency of the beat noise, the order of the driving force source and the rotation speed of the driving force source.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a device for determining beat noise (humming noise) that may occur in a vehicle, and more particularly to a device for identifying beat noise generated in a drive mechanism provided for each wheel and its source. [Background technology]

[0002] A vehicle travels by transmitting the driving force generated by a power unit such as an engine or a motor from the wheels to the road surface. Therefore, sound is inevitably generated by the power unit, the transmission mechanism that transmits the driving force, which is the output of the power unit, and the contact points between the wheels and the road surface. Sounds that are unpleasant to the ears of vehicle passengers are considered to be so-called abnormal sounds and are to be silenced or blocked as much as possible, but even if measures such as silencer or sound blocking are taken, it is first necessary to identify the frequency, sound pressure, or source of the abnormal sound to be addressed. Patent Document 1 describes an apparatus that analyzes sound or vibration generated in a power transmission mechanism of a vehicle. The apparatus described in Patent Document 1 is an apparatus that acquires data on sound or vibration generated with the rotation of a specific rotating body that constitutes the power transmission mechanism of a vehicle, and imports and analyzes data on the number of revolutions of the rotating body, analyzes the frequency of the sound or vibration, and determines an order according to the specifications of the rotating body from the sound or vibration data. If there is a sound or vibration that matches the order, the rotating body is deemed to be the source of the sound or vibration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-98984 A Summary of the Invention [Problem to be solved by the invention]

[0004] The device described in Patent Document 1 is designed to analyze sounds or vibrations generated from a power transmission device. However, not only are sounds or vibrations generated from a power transmission device diverse, but various sounds or vibrations are also generated depending on the running state of the vehicle. In contrast, the device described in Patent Document 1 analyzes these sounds or vibrations without distinguishing them, which may increase the load on the device. In particular, since beat sounds generated in response to specific vehicle behavior are a composite of sounds generated from multiple sources, the device described in Patent Document 1, which is configured to simply analyze the acquired sounds or vibrations, is unable to grasp the beat sounds, and there is still room for improvement in terms of reducing or eliminating abnormal sounds that cause discomfort.

[0005] The present invention has been made in light of the above-mentioned technical problems, and aims to provide a device that can determine the presence of beat noise so as to enable measures to be taken to reduce the beat noise that may occur when the vehicle is in a specific driving state. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a beat sound detection device for a vehicle that has a plurality of wheels, each of which is provided with a driving force source, and that analyzes sound data generated by the vehicle while the vehicle is running to determine beat sounds, the device extracts sounds with a predetermined sound pressure or higher from the sounds as protruding sounds, and determines, from the protruding sounds, protruding sounds whose frequency difference is within a predetermined range and whose sound pressure difference is less than a predetermined value as beat sounds, and determines whether the sound source of the determined beat sound is the driving force source based on the frequency of the determined beat sound, the order of the driving force source, and the rotation speed of the driving force source. Effect of the Invention

[0007] According to the present invention, when a difference in rotation speed of the driving force source occurs due to a difference in ground load between the front and rear of the vehicle or a difference between the inner and outer wheels when turning, and as a result a beat noise occurs, if the beat noise is a prominent sound, it is determined that it is a beat noise based on the frequency difference and the sound pressure difference. In other words, the beat noise that occurs depending on the running state of the vehicle can be detected as an abnormal sound. In addition, since it can be determined whether the source of the abnormal sound is the driving force source or not, it becomes possible to take measures against the abnormal sound to improve the ride comfort. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram for explaining the functional configuration of the beat sound determination device. [Diagram 3] 4 is a flowchart illustrating an example of control executed in the embodiment of the present invention. [Figure 4] 13 is a map showing an example of a time axis color map of a protruding sound with the colors omitted. [Diagram 5] (A) is a waveform diagram of the protruding sounds generated from the left and right driving force sources, and (B) is a waveform diagram of the beat sound. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Next, the present invention will be described based on the embodiment shown in the drawings. Note that the embodiment described below is merely one example of a specific embodiment of the present invention, and is not intended to limit the present invention.

[0010] 1, a vehicle 1 according to an embodiment of the present invention is configured to have a plurality of wheels 2, and to run by driving at least any two of the wheels 2 by a driving force source 3 provided corresponding to each of the wheels 2. A typical example of this is an all-wheel drive vehicle in which each of the four wheels is provided with a driving force source 3, and another example is a four-wheel drive vehicle in which a pair of two wheels are provided at the front and a pair of two wheels are provided at the rear, and a driving force source 3 is provided for each pair of the wheels.

[0011] Although not specifically shown, the driving force source 3 includes an electric motor (motor) or an electric motor with a generating function (motor-generator) as a power device that outputs driving force, and a transmission mechanism that transmits the output torque to the wheels 2. The transmission mechanism may be a gear-type reduction mechanism, or may be a transmission mechanism that can change the gear ratio.

[0012] A controller 4 is provided that controls the driving force source 3 to drive the vehicle 1. The controller 4 is a collective term for a number of control units (ECUs), and includes a motor ECU 4a that controls the motor or motor generator (hereinafter collectively referred to as the motor) of the driving force source, a transmission ECU 4b that controls the gear ratio when the driving force source 3 is equipped with a transmission mechanism, and a steering ECU 4c that steers either the front or rear wheels 2. Note that these ECUs 4a, 4b, and 4c may be control units mainly composed of a microcomputer, similar to control devices mounted on general vehicles, and are configured to perform calculations using data input from various sensors or pre-stored data, and to output the results of the calculations as control command signals to control the driving force source 3.

[0013] The beat sound detection device 5 in the embodiment of the present invention is configured to extract beat sounds from abnormal sounds generated by the vehicle 1 while it is traveling and to determine the source of the sounds, and a functional configuration of one example is shown in a block diagram in Fig. 2. The beat sound detection device 5 is mainly configured to use a microcomputer, and is configured to perform calculations according to a predetermined program using input data and pre-stored data, and to output the results of the calculations as the determination results to the outside. Therefore, a sound collection microphone 6 is connected to the beat sound detection device 5, and the sound collection microphone 6 collects sounds generated by the vehicle 1 (particularly abnormal sounds generated by the motor and transmission mechanism of the driving force source 3) and the sound acquisition unit 7 acquires data related to the sounds.

[0014] The beat sound determination device 5 is provided with an acoustic analysis unit 8 that analyzes the data acquired by the acoustic acquisition unit 7. The acoustic analysis unit 8 is configured to divide the sound collected by the sound collection microphone 6 into frequencies, detect the sound pressure and order of the sound of each frequency, and further digitize and output them. Furthermore, in the embodiment of the present invention, the acoustic analysis unit 8 is configured to use AI (artificial intelligence) to extract abnormal sounds contained in the collected sound and beat sounds caused by abnormal sounds, and detect their frequencies and sound pressures. An example of a solution that fulfills such a function may be "Monone" (registered trademark) by NTT DATA CCS Corporation or "Momsym" included therein.

[0015] Furthermore, the beat sound determination device 5 includes a determination unit 9 that determines whether the source of the beat sound is the driving force source 3. The determination unit 9 acquires, for example, information related to the rotation speed of the motor in each driving force source 3. The determination unit 9 also acquires, for example, information related to the steering angle of the vehicle 1 from the steering ECU 4c. The determination unit 9 also acquires, for example, information related to the vehicle speed of the vehicle 1 and information related to the gear ratio of the left and right transmission mechanisms of the vehicle 1 from the transmission ECU 4b. When the steering angle of the vehicle 1 is not "zero", the order of the abnormal sound calculated by the acoustic analysis unit 8 changes with the change in the steering angle of the vehicle 1, and the frequency of the abnormal sound calculated by the acoustic analysis unit 8 matches the difference in the rotation speed of the motors on both the left and right sides of the vehicle 1, the determination unit 9 identifies the part of the transmission mechanism that is causing the abnormal sound by comparing the gear ratio of the vehicle 1 with the frequency of the abnormal sound.

[0016] Next, an example of control in an embodiment of the present invention will be described with reference to the flowchart shown in Fig. 3. First, the abnormal sound recording data is subjected to frequency analysis (step S1). The abnormal sound recording data is data collected and recorded via the sound collecting microphone 6 while the vehicle 1 is running. The abnormal sound is a sound extracted from the sound collected via the sound collecting microphone 6, and can be obtained by AI analysis using Momsym as described above, and its frequency is detected.

[0017] Next, protruding sounds are extracted from the time axis color map (step S2). A protruding sound is an abnormal sound whose sound pressure is equal to or greater than a predetermined sound pressure. The acoustic analysis unit 8 can output the analysis results as numerical data, and can convert the output into image data and display it on a specified display. Therefore, a protruding sound appears as a prominent line on the time axis color map.

[0018] An example is shown in FIG. 4. FIG. 4 is a schematic map obtained by rewriting the measured data, and is obtained when the vehicle 1 is turning. In FIG. 4, the vertical axis indicates frequency, the horizontal axis indicates time, and the sound pressure is represented by the thickness of the line. Therefore, the solid line in FIG. 4 is a protruding sound with a sound pressure greater than a predetermined value. For example, if an abnormal sound is generated from the left and right driving force sources 3 due to some cause, if the vehicle 1 is running straight, the rotation speeds of the left and right wheels 2 are equal, so the frequency of the abnormal sound is the same, and it appears as a single line on the map. In contrast, when the vehicle 1 turns, a difference in rotation speed occurs between the wheels 2 on the inner circumference side and the wheels 2 on the outer circumference side, so that the frequency of the abnormal sound generated from the driving force sources 3 corresponding to each wheel 2 differs. An example is shown in Fig. 5(A), where the waveform line L1 indicates the abnormal noise from the inner circumference side driving force source 3, and the waveform line L2 indicates the abnormal noise from the outer circumference side driving force source 3, with the frequency of the abnormal noise from the inner circumference side driving force source 3 being slightly smaller than the frequency of the outer circumference side driving force source 3. Therefore, these prominent noises appear as two separate lines in the map shown in Fig. 4.

[0019] The waveform line L3 obtained when these abnormal sounds are combined is shown in Fig. 5(B). The so-called combined sound shown by this waveform line L3 is a beat sound (beat) whose sound pressure reaches maximum and minimum in a period corresponding to the difference between the frequency of the abnormal sound shown by the waveform line L1 and the frequency of the abnormal sound shown by the waveform line L2. Therefore, in Fig. 4, the line indicating the protruding sound when the beat sound is occurring is split into two and appears as a smooth line that increases and decreases in a long period (a period corresponding to the difference in the frequency of the protruding sounds).

[0020] In this way, the frequency and frequency difference of the protruding sound extracted from the abnormal sound can be obtained, and in the flow chart shown in FIG. 3, it is determined whether or not the frequency difference (protruding sound frequency difference) is within a predetermined range (0.5 Hz to 20 Hz, as an example) (step S3). Since beat sounds are caused by a slight difference in frequency between sounds occurring simultaneously, the frequency difference, which is a requirement for beat sounds, is determined in step S3. Therefore, if the frequency difference of the protruding sounds is outside the above-mentioned predetermined range, it is simply a different protruding sound. Therefore, if the result of the determination in step S3 is "no", it is determined that it is not a beat sound (step S4) and the process returns.

[0021] On the other hand, if the result of the judgment in step S3 is "Yes", it is judged whether the difference in the level (sound pressure) of the protruding sound shown by the two lines in FIG. 4 is within a predetermined sound pressure (for example, 6 dB) (step S5). Since the driving force sources 3 of the vehicle 1 essentially operate in the same way, even in a running state in which the rotation speed difference occurs in the wheels 2, such as turning, there is no particularly large difference in the sound emitted from those driving force sources 3. This is also true for the above-mentioned protruding sounds, and even if there is a difference in sound pressure, it is only slight. In other words, if the sound pressure difference of the protruding sounds exceeds the predetermined sound pressure, those protruding sounds are not protruding sounds that cause beat sounds. Therefore, if the result of the judgment in step S5 is "Yes", a beat sound judgment is made (step S6), and if the result of the judgment in step S5 is "No", the process proceeds to the above-mentioned step S4, where it is judged that the sound is not a beat sound, and the process returns.

[0022] After determining whether the beat sound is included in the acquired abnormal sound, a process is performed to identify the part causing the beat sound. First, the vehicle model is acquired based on the vehicle identification number (VIN: Vehicle Identification Number) of the vehicle 1 (step S7). Since the structure of the driving force source 3 can be identified by acquiring the vehicle model, the order of the driving force source 3 (particularly the transmission mechanism) of the vehicle model is acquired (step S8). Here, the order is the order of vibration generated in the driving force source 3, and in the case of a vehicle 1 equipped with a gear transmission mechanism, it is a unique value determined by the number of teeth of the gear mechanism. Therefore, the order is obtained in advance and input or stored in the beat sound determination device 5. Following or immediately following step S8, the rotation speed of the motor (MG) constituting the driving force source 3 is read (step S9).

[0023] Since the order of vibration (sound) expected to occur in the driving force source 3 is obtained based on the order determined by the structure of the driving force source 3 and the rotation speed of the motor, in step S10, it is determined whether the frequency of the above-mentioned protruding sound that is the cause of the beat sound matches the order of vibration (sound) expected to occur in the driving force source 3. If the result of the determination in step S10 is "Yes", the part causing the abnormal sound (protruding sound) that is the cause of the beat sound is identified (step S11), and then the process returns. That is, the part causing the abnormal sound is the part whose order matches the protruding sound frequency. On the other hand, if the result of the determination in step S10 is "No", it is determined that the determined beat sound is not caused by an abnormal sound generated by the driving force source 3 (step S12), and the process returns.

[0024] It should be noted that the above-mentioned embodiment is merely for specifically explaining the present invention, and the present invention is not limited to the above-mentioned embodiment. For example, the beat sound determination device of the present invention may be configured to be mounted on a vehicle, or may be configured to be fixed outside the vehicle. Also, it may be incorporated into a part of the above-mentioned Momsym, or may be configured as an independent determination device. Furthermore, the vehicle targeted by the present invention is not limited to the vehicle configured as shown in FIG. 1 above, and in short, it is sufficient if it is a vehicle provided with a plurality of driving force sources including a motor and driving wheels corresponding to each driving force source. [Explanation of symbols]

[0025] 1 vehicle 2 wheels 3. Driving force source 4. Controller 5 Beat sound detection device 6 Sound collection microphone 7 Sound acquisition section 8 Acoustic analysis section 9 Judgment section 4a Motor ECU 4b Transmission ECU 4c Steering ECU L1,L2,L3 waveform line

Claims

[Claim 1] A beat noise determination device for a vehicle having a plurality of wheels, each of which is provided with a driving force source, for determining a beat noise by analyzing data of a sound generated from the vehicle while the vehicle is traveling, comprising: extracting sounds having a predetermined sound pressure or higher from the sounds as prominent sounds; Among the protruding sounds, a protruding sound having a frequency difference within a predetermined range and a sound pressure difference equal to or less than a predetermined value is determined to be a beat sound, Based on the determined frequency of the beat sound, the order of the drive force source, and the rotation speed of the drive force source, it is determined whether the sound source of the determined beat sound is the drive force source. A beat noise detection device for a vehicle.

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